Gun fire control apparatus



33*2 3b W4 7 a 658 a 277 SR Nov. 10, 1953 A. P. DAVIS ETAL 2,658,277

GUN FIRE CONTROL APPARATUS Filed Dec. 19, 1938 2 Sheets-Sheet 1 A W MMA Nov. 10, 1953 A. P. DAVIS ET AL 2,658,277

GUN FIRE CONTROL APPARATUS Filed Dec. 19, 1938 2 Sheets-Sheet 2 [B J yfi 2 k g 52 Q U20 53 i5 $1 3% a: a a

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Patented Nov. 10, 1953 GUN FIRE CONTROL APPARATUS Arthur P. Davis, Stamford, Conn., and James K. Macomber, Rockville Centre, N. Y., assignors to Arma Corporation, a corporation of New York Application December 19, 1938, Serial No. 246,680

Claims. 1

This invention relates to gun fire control apparatus and has particular reference to angular rate control mechanism for following a moving target in train and/or elevation from a point on an unstable datum plane such as the deck of a ship.

Angular rate control mechanisms of this character may form part of gun fire control director apparatus, whose function it is to set up and solve the mathematical relations between a moving target and own ship in order that the gun or guns may be properly maintained directed on a moving target, such as aerial or surface craft, depending upon requirements. The invention will be described in connection with a problem diagram upon which the design of one of such directors, includin the angular rate control mechanism, is based, and this diagram and the apparatus are illustrated in the accompanying drawings, in which:

Figure 1 illustrates the aforementioned problem diagram;

Figure 2 is a reduced view of a portion of the problem diagram of Figure 1, showing the relations between the mutually perpendicular components of the angular rate of target movement;

Figure 3 is a reduced view, similar to Figure illustratin the vector relations between the components of the relative linear rate of the target;

Figure 4 is a schematic diagram of the rate control mechanisms constructed in accordance with this invention, including a gyroscopic system;

Figure 5 is a partial view illustrating apparatus for erecting the azimuth gyroscope into the horizontal plane;

Figure 6 is a partial view illustrating a gear assembly for transmitting power to the azimuth gyroscope follow-up ring, and

Figure 7 is an enlarged fragmentary perspective view of a lost motion connection between aligned shafts.

Problem analysis Referring to the problem diagram illustrated by Figure 1, T is the target which may be an aeroplane, for example, moving in a straight line at a uniform speed, and D represents the gun fire control director mounted on own ship. R is the present line of sight and its length also represents the present range from the director D to the target T. Vector dB in Figure 3 represents the instantaneous linear range rate, determined usually from the average trend of several imm diat ly us bservat ons, The angle a is the present position angle between a stabilized horizontal plane in the director and the present line of sight R.

The point T is the advance predicted target position, which also represents the intended projectile impact point. The target displacement AS is the component of the distance moved by the target T perpendicular to the present line of sight R in the a. plane relative to own ship during the time of flight of the projectile. A0 is the advance position angle between the advance predicted line of sight AR and the stabilized horizontal plane in the director D. The length of AR also represents the advance predicted range from the director D to the advance predicted target position T.

It is required to determine the angular values of lateral deflection LD and the vertical deflection VD through which the gun must be moved from the present line of sight R in order that a projectile fired when the target is in the present line of sight will strike the target at the advance predicted position T. This discussion, of course, neglects for the purposes of the present problem the usual correction factors, and assumes that the trajectory of the shell is a straight line. On these premises and given the values of 0, a. and A0, LD and VD may be determined from the equations:

Sin A0=sin 0 cos a+cos 0 sin 0: sin

sin 0: cos cos 0 cos A0 005 a cos LD Sin LD= Cos VD= In order to determine the angle a. between R and AR, it is first necessary to determine the range base RB and the target displacement AS in the a. plane perpendicular to present line of sight. The target displacement AS is obtained by multiplyin the target displacement angular rate da. by the present range R to get target displacement linear rate ds, which is then multiplied by the projectile time of flight TF. The range base Re is obtained by multiplying the range rate dR by the time of flight TF to give the line of sight projection of the target displacement AR and subtracting it from or adding it to present range R, as the case may be. The range base RB and the target displacement AS are then composed to obtain the advance predicted range AR. and the angle (1.. These values may be determined mathematically in accordance with the following equations:

a=tan' AR:'\/AS2+RB2 Having values for 0, and a, the equations given above may be solved to give VD, LD, and A0. The solution is performed with facility by graphic mechanism forming no part of the present invention. VD and LD are then corrected for additional ballistic corrections before they are transmitted to the gun train and elevation controls. It is also necessary to correct for the angular movement of the unstable ship deck, which is preferably resolved into its two components, viz. level L, which is the vertical angle between the projection of the present line of sight R on the stabilized horizontal plane, and the plane of the deck, and cross level CL which is the angle measured perpendicular to the deck between the plane of the deck and a line in the horizontal plane perpendicular to the line of sight projection in the horizontal plane.

The angular rate control mechanisms of the present invention serve to measure the mutually perpendicular angular target rates in elevation and bearing do and d respectively, with reference to stabilized horizontal and vertical planes in the director, and to move the director automatically in train and elevation in response to the measured rates. Angular bearing rate dB is measured in a slant plane from a vertical plane of reference in the director. These rates are obtained by following the target in train and elevation by the operation of the trainers and pointers handwheels as described below.

The angular rates and dc are mechanically integrated over elapsed time. The output of 0, corrected for the pitch and roll of the ship by inputs of level L and cross level CL from a stable element, is transmitted to the pointers and trainers telescopes mounted on the director.

Inasmuch as angular bearing rates dc are measured in a slant plane containing all horizontal lines perpendicular to the line of sight, the integrated angular bearing rate must be divided by the cosine of the position angle 0 in order to convert it to integrated horizontal bearing fdHp which is employed for training the director to follow the target. This conversion is expressed by the equation:

The manual correction which is applied to bearing in the slant plane is added to I'd 8 before the latter is divided by cos 0.

In accordance with the invention, the pointer or trainer brings his telescope on to the target and closes the rate control switch. He then continues to turn his handwheels to as to remain rate into the director. The gearing constants are such that the rate may be set within a few seconds of time. After the rates are set in, the rate control mechanisms will cause the telescopes to automatically follow the target so long as the relative angular rate of the target with respect to the own ship remains constant. In general, the elevation and bearing rates will not remain constant and it will be necessary for the trainer and pointer to frequently correct the rates, keeping the crosshairs on the target, by small motions of the handwheels with the rate control switch closed.

Gyroscopic system Referring to Figure 4, numeral I00 designates the level gyroscope assembly which establishes the horizontal reference plane in the director and which comprises a vertical axis gyroscope IOI mounted on a gimbal support I02 on bail I03 journalled in bracket I04 about a vertical axis and constantly rotated about that axis by a slow speed motor I05 through gears I06. The rotation of the gyroscope and gimbal support IOI, I02 cooperating with a ballistic system provides an erecting torque tending to maintain the gyroscope IOI vertical under all conditions of operation, as is explained in greater detail in copending application Serial No. 95,722, filed August 12, 1936, by applicant Davis.

The bracket I04 is supported on a vertical ring I01 having opposite pivots I08 and I08 journalled in horizontal outer gimbal ring I 09 having opposite pivots H0 and III displaced from ring I01, pivots I08 and I08, and in turn journalled on brackets II2 fixed on the director casing I2. At the upper end of the ring I01 are mounted the level and cross-level follow-up coils H6 and H1, respectively, which are energized inductively by an electromagnet II8 on the casing of gyro IOI. The pivot III on outer gimbal ring I09 is hollow and is fitted with a toothed sector I26 driven by a worm wheel I21 for rotating the outer gimbal ring I08 about the crosslevel axis IIO, III. Journalled in pivot I II is a shaft I28 fitted with pinion I29 engaging a sector I30 secured to bracket I04 for rotating the latter about the level axis.

Directly above the level gyro IOI is the azimuth gyro assembly I35 which comprises a horizontal axis gyroscope I36 mounted on a gimbal support I31. The gimbal support I31 is pivoted on outer ring I38, which is secured to a supporting bail I39. Secured to the outer gimbal ring I38 is a second vertical bail I4I, displaced horizontally 90 from the bail I39 and extending downwardly and provided with a vertical shaft I42 on which is journalled a hollow pivot I42 to which the supporting arms I49 of a follow-up ring I50 are secured. The follow-up ring I50 is provided with upwardly-extending supporting arms I5I terminating in a hollow pivot I 5| from which the gyroscope supporting bail I39 is suspended on a suitable cable I40.

Journalled on the pivot I5I' and the pivot I42 is a vertical ring I52 which is supported on the pivots I53 and I54, formed on outer gimbal ring I51. The outer gimbal ring I51 is provided with opposit shafts I58 and I59, displaced horizontally 90 from pivots I53 and I 54, by means of which it is supported Within the director housing. The pivot I 53 is connected by a link I60 to pivot I08 on outer gimbal ring I09 of the level y o s y so that the motion of the on the tar et, and by so doing he sets the a gular 5 u er g m aI ring I09 about the cross-level axis is transmitted to the outer gimbal ring I51 of the azimuth gyro. Similarly, the vertical ring I52 is provided with a hollow shaft I6I which is connected by means of an arm I62 and link I64 to an arm I63 on the pivot I08 on vertical ring I01 of the level gyro assembly I00, so that rotation of the vertical ring I01 about the level axis is transmitted to the vertical ring I52 of the azimuth gyro I35 assembly. By means of these linkages, the rings in the azimuth gyro are at all times maintained in the same horizontal plane by the level gyro assembly I00.

Where it is not desired or not practicable to connect the gimbal system of the azimuth gyro I35 with the gimbal system of the level gyro I00, follow-up mechanisms may b used in a known manner, so that the rings of the azimuth gyro assembly I35 are maintained level at all times.

Inasmuch as the azimuth gyro I36 is not fixed in space, it may tilt from the horizontal by as much as 15 in an hour, due to the rotation of the earth about its axis. It becomes necessary, therefore, to restore the azimuth gyro to the desired position in the horizontal plane at regular intervals and this may be accomplished by providing an electrical contact I9I on the gimbal ring I38, and insulated therefrom, which is adapted to engage contact I9I' on the gyro shaft when the latter has tilted 15 from the horizontal. This closes a circuit to an erecting motor I92 mounted on one of the supporting arms II of the ring I50 as is illustrated in greater detail in Figure 5. When the erecting motor I92 is energized, the director train motor I13 is electrically disconnected by means of switching circuits, not shown, but which may be of any conventional disconnect type.

Under certain conditions it may be preferable to actuate the erecting motor manually, in which case the switch I9I may be made to operate a signal device (not shown) indicating to the operator that the azimuth gyro has tilted to a position Where it may introduce errors in the results obtained by the apparatus. The operator may then, befor the beginning of a run, actuate the erecting motor I92 to restore the azimuth gyro I36 to its proper position in the horizontal plane as indicated below.

A. pin 298 on gimbal ring I38 engages either stop 299 or 300 on follow-up ring I50, when electromagnet I69 is angularly displaced approximately 15 from its neutral position of alignment with follow-up coil I68.

The motor I92 drives a gear I93 meshed with gear I94 from which gears the pins I95 and I96, respectively, project. The rotation of the gears I93 and I94 moves the pins I95 and I96 toward each other until one of the pins I95 or I96 engages a vertical pin I92 which is mounted on an arm I93 secured. perpendicularly to the inner gimbal ring I31 at the point where it is connected to pivot I94. The resulting precession of the gyro I36 in azimuth is limited by the engagement of pin 288 with either stop 299 or 300, and as the director train motor I 13 is electrically disconnected, the effect produced by limiting the precession of the gyro I36 in azimuth erects the axis of the gyro into the horizontal plane. The gears I93 and I94 rotate until the pin I92 is centered between the gear pins I95 and I96. In this position, the inner gimbal ring I31, and thus th axis of rotation of the azimuth gyro I36, lie in the horizontal plane. Connections to the coils and switches on the gyro gimbal rings are made through suitable brushes and slip rings (not shown).

On the outer periphery of the azimuth gyro ring I50 a ring gear I65 is formed which is driven by the gearing I66 from a shaft I61 concentric with hollow supporting shaft I59. Inasmuch as the ring I50 moves relatively to the outer gimbal ring I51 due to inputs of level to the azimuth gyro assembly I35, a special gearing assembly is required to rotate the ring I50. Any suitable flexible coupling may be used, such as is shown in Figure 6, for example, in which gear I66 is connected to shaft I61 through a universal coupling I91, and a cooperating slot and pin combination I98. The gear I66 is maintained engaged with ring gear I65 by a bracket and roller assembly I99, which is prevented from moving with ring I50 by the slotted arm II3. Ring I50 carries follow-up coil I68 energized inductively by an electromagnet I69 on the azimuth gyro gimbal ring I38. Follow-up coil I68 is connected by wires I10 to a follow-up control system I1I which may be of the electronic type, and which is connected by wires I12 to the director train motor I13. A follow-up system that is suitable for this purpose is disclosed in copending application Serial No. 53,736, filed December 10, 1935, by applicant Davis now Patent 2,421,247. The mechanical output of train motor I13 drives a ring gear I14 on the director housing through a pinion I15, causing the director to train right or left as may be required by the movement of the target.

The level and cross-level follow-up coils, H6 and I I1, respectively, of the level gyro I00 are also connected to the follow-up control IN by wires I16 and I11, respectively. The signals from the follow-up coils are amplified by follow-up control HI and the amplified signals are transmitted through the wires I18 to operate the level motor I19, giving it a mechanical output of level L plus f(C'L).

Similarly, amplified signals are supplied through the leads I to the CL motor I8I, providing a mechanical output of cross-level CL. The mechanical output of L+f(CL) from the motor I 19 is transmitted through the gearing I82, shaft I83, gearing I84, shaft I85, gearing I86, shaft I 28, gear I29, sector I30, bracket I04 and bail I01, rotating the latter about the L axis in the proper direction to reduce the signal from the L follow-up coil I I6 to zero. The function of CL designated ,1 (CL), is a correction which must be added to the L input to compensate for relative motion between the L input shaft and the CL gimbal element.

The mechanical output of CL from the motor I8I is transmitted through the gearing I81, shaft I88, gearing I89, shaft I90, worm I21 to worm segment I26 on outer gimbal ring I09 of level gyro I 00. The ring is thereby rotated in the proper direction about the CL axis to restore the CL follow-up coil II1 to the zero signal position directly over the electromagnet I I8. Further details of the construction of the lever gyroscope system I00 and its follow-up mechanism are i1- lustrated and described in copending application Serial No. 53,736, filed December 10, 1935, by applicant Davis.

By means of the L and CL follow-ups, together with their motors and the linkages between the two gyro systems, the rings of both the level I00 and the azimuth I 35 gyro systems are at all times maintained level regardless of the roll and pitch of the ship. The whole gyro system thus provides a stabilized horizontal reference plane and a vertical plane of reference in the director.

Angular rate control mechanism The angular rates in elevation (do) and bearing (dp) of the moving target are determined by direct measurement of the movements of the target with the pointers and trainers telescopes by means of their respective handwheels in conjunction with angular rate control mechanism.

Considering the trainers rate control mechanism in trainers handle box I0, it comprises the double handwheel 200 connected through the gearing 20I and shaft 202 to an electromagnetic clutch 203. The clutch 203 is supplied with power from the D. C. line through the wires 204 and a switch 205 which is conveniently located on the right handle of the trainers hand Wheel 200. The driven disc 206 of the clutch 203 is connected through a limited lost motion mechanism to a shaft 201 on which a pinion 208 is secured. The lost motion mechanism may comprise any suitable means such as that disclosed in Fig. 7 in which a pin 294 on the driven shaft 295 moves in a narrow slot 296 formed in a lateral extension 201 on the end of the aligned shaft 201, although obviously any other suitable mechanism may be used. The mechanism allows a few degrees play between the shaft 295 and the shaft 201, so that the stabilization of the telescopes may be improved by small manual adjustments to eliminate the effects of lost motion, without aifecting the rate set up in the rate control mech anism. The pinion 208 engages a rack 209 having an elongated gear 2I0 and roller 2 II engaging a disc 2I2 rotated at a constant speed by a suitable source of power, which may be the mechanical time system of the director, generally indicated by the unit 291. The time system may be of the type disclosed in copending application Serial No. 93,138, filed July 29, 1936, by Clifton T. Foss, now Patent No. 2,138,912, issued December 6, 1938. This assembly comprises the trainers integrator which integrates change in lateral hearing do over elapsed time.

The rotation of the roller 2II which is integrated change in lateral bearing do is transmitted by gear 2I0 and pinion 2I3, shaft 2 I4, slip clutch 2l5, gearing 2 I 6, shaft 2 I1, and gearing 2 I8 to one gear of a differential H9. The other gear of the differential 2I9 receives an input of change in lateral hearing from the shaft 202 through the gearing 220. The output of the differential 2I9 is thus the sum of integrated lateral bearing from the shaft 2H and change in the lateral hearing from the shaft 202. The slip clutch 2I5 prevents the integrator roller 2 I I from slipping on the disc 2I2 when the shaft 2I1 reaches its limit at the maximum value of f (1 8.

The output of the differential 2I 9, which is the sum of integrated lateral bearing and change in lateral bearing, is transmitted through pinion 222, connected to the output of the differential 2I9, to a divider 22I, where it is divided by the cosine of the position angle 0. The cosine divider 22I includes gear 223 engaging pinion 222, and carrying the roller 224 engaging a disc 225 mounted on a shaft 226. The rotation of disc 225 is transmitted through gearing 221, shaft 228, gearing 229, shaft 230, gearing 23I, and gearing 232 to a differential 233, the other input to which is f(L) plus f(CL), from the level motor I 19 through the shaft 234, gearing 235, and shaft 236.

The output of the differential 233 which is horizontal fi-l-flL) +f(CL) is transmitted through the gearing 231, shaft 231' and the gearing 238 to shaft I61 which then actuates the gearing I66 and causes the ring gear I65 on the azimuth follow-up ring I50 to move in response to the rotation of the trainers handwheel 200. The movement of the azimuth follow-up ring I50 is opposite to the desired direction of train, so that the director will train in the proper direction to keep the telescope cross-hairs on the target.

Division of the quantity integrated lateral bearing plus change in lateral bearing is accomplished by changing the position of the roller 224 with respect to the disc 225. Attached to the free end of the gear 223 is a vertical slide 239 which is formed with a slot 240 in which a pin 2 on gear 242 is adapted to slide. The gear 242 is rotated about its pivot 242' in accordance with the magnitude of the position angle 0 which is received from the pointers rate control mechanism II through gear 244 and the shaft 245.

It will be evident that as the gear 242 rotates through the angle 0, the slide 239 will be moved horizontally a distance proportional to cosine 0 and the roller 224 will move a corresponding radial distance along the disc 225. The output of the disc 225, therefore, is the input of integrated lateral bearing plus change in bearing from the pinion 222 divided by cosine 0.

In case it is desired to return the trainer rate control mechanism I0 to the zero position, such as for example, in directing the director on different target, the trainers resetting device is actuated. This resetting device comprises a reset handle 246 on shaft 250 connected to shaft 201 through gearing 25 I. By rotating handle 246, the trainers rate control mechanism may be accordingly reset.

The pointers rate control mechanism II is substantially identical in construction to the trainers rate control mechanism I 0 so that it will not be necessary to repeat the description except to point out differences in construction. Thus, the integrated angular elevation plus the change in elevation, which is the output of the differential 2I9', is transmitted to the cosine divider 22I of the trainers rate control mechanism I0 through the shaft 245 as described above. This output is also transmitted through the gearing 254, shaft 255, gearing 256, and shaft 251 to an elevation dial 258, which indicates elevation of the target T above the stabilized horizontal reference plane set up in the director by the level gyro assembly I 00.

The elevation output is also transmitted from the shaft 251 through the gearing 259 to one of the gears of a differential 260 whose other input is L+ (CL) from the level motor I19 through the shaft 234. The output of the differential 260 is thus the position angle 0+L+f(CL) which is then transmitted through shaft 26I, gearing 262, shaft 263, to a pinion 264 in the system of the pointers and trainers telescopes I3 and I 4. The pinion 264 engages the drive gear 265 of a triple gear assembly 266 which includes the gears 265, 261 and 268, mounted on a hub 269. Within the hub 269 is a shaft 210 which receives a mechanical input of CL from the cross-level motor IBI through shaft 21I, gear 212 and gear sector 213. This input of CL causes the telescopes I3 and I4 to rotate about the shaft 210 to keep the telescope crass-hairs on the target as the ship pitches and r0 s.

The gears 268 and 261 which provide an output of 0+L+f(C'L) are engaged by the pinions 214 and 215, respectively, which are mounted on the shafts 216 and 211, respectively. Inasmuch as the shafts 21B and 211 rotate about the triple gear in response to the CL input to the shaft 210, it will be evident that a differential action takes place which removes 1*(013) from the input so that the input to the movable prisms I3 and I4 of respective telescopes I3 and I4 and open sight is +L. The telescopes I3 and I4 and open sight accordingly are elevated and depressed by the L input in order to compensate for the roll of the ship so that the telescope cross-hairs may be maintained on the target.

A mechanical input of CL is also transmitted through the gearing 218, shaft 219, gearing 280 and shaft 28 I, to a cross-level indicator 282 which, indicates the magnitude of the cross-level angle due to pitch and roll of the ship. The same CL input is also transmitted from the shaft 219 through the gearing 283 to one side of a diiferential 284, whose other input is L+f(C'L) from the level motor I19 through the shaft 234, gearing 285, shaft 288, gearing 281 and shaft 288. As a result of the differential action, the mechanical input of CL from the shaft 219 is subtracted from the mechanical input of L+f(CL) from the shaft 288. Hence, the output of the diiferential 284 is L alone, which is then transmitted through a shaft 289 to a level indicator 290.

Operation In operation, the trainer rotates hi handwheel 200, displacing the azimuth gyro I35 follow-up ring I50 and causing the director to train in a direction opposite to the direction of displacement of the follow-up ring I50 to restore the follow-up coil I68 to its neutral position with respect to the electromagnet I69. This operation continues smoothly until the crosshairs of the trainers telescope I3 are centered on the target. Thereupon the trainer closes the switch 205, thus energizing the electromagnetic clutch 203 and transmitting an input of lateral bearing rate to the trainers rate control mechanism I0. By continuously following the target with the switch 205 closed, the roller H I is moved radially along the integrator disc 2I2 until it rotates at a speed corresponding to the lateral bearing rate dfl. The rotation of the roller 2II is transmitted to differential 2I9 where it is added to the change in lateral bearing as transmitted through gearing 20I, shaft 202, and gearing 220 to differential 2| 9. The sum is transmitted to the cosine divider 22I and the output of the divider is transmitted through shaft 226, gearing 221, shaft 228, gearing 229, shaft 230, gearing 23I and 232 to differential 233 where level+f(CL) is added to it. The sum is transmitted through gearing 231 and 238, shaft I61 and gear I66 to the follow-up ring I50 of the azimuth gyro system I35 to displace it at a rate equal to the bearing rate of the target with respect to the ship. This causes the director to train automatically so that only slight rotation of the handwheel 200 is necessary to correct the lateral bearing rate should the telescope crosshairs go off the target.

The pointer meanwhile, likewise rotates his handwheel 200, elevating the telescopes I3 and I4 and open sight until the crosshairs are centered on the target. The switch 205' is then closed, energizing the electromagnetic clutch 203', and causing the roller 2| I to move radially along the integrator disc 2I2' until it rotates at a speed corresponding to the angular rate of elevation d0. Further rotation of the handwheel 200' is necessary only to correct the elevation rate should the telescope crosshairs go off the target.

The driven discs 206 and 206' of the clutches 203 and 203', respectively, are both provided with suitable brakes 293 and 293' which are continually maintained under tension. These brakes prevent the driven shafts 29I and 29I' of the dB and d0 angular rate control mechanisms from being driven to zero under the influence of the biasing springs on the follow-up heads of the (da) solver disclosed in application Serial No. 246,681 filed December 19, 1938, when the switches 205 and 205 are opened. The elevation rate do and the bearing rate dc are introduced as inputs into the computer of the director by shafts 29I' and 29I, respectively, and are received as instantaneous angular rates determined by following the target T in elevation and bearing with the respective director sights I3 and I4 by rotation of the trainers and pointers handles as described. Suitable indicators driven by shafts 29I and 29I may also be provided.

It will be evident that the trainers and pointers angular rate control mechanisms I0 and II will keep the crosshairs of the telescopes I3 and I4 continually on the moving target '1 with a minimum operation of the trainers or pointers handwheels 200 and 200', respectively. It is assumed, of course, that the target meanwhile is moving in a straight line at a constant speed. Any changes in target course or speed, however, may be instantly corrected for by operation Of either the trainers or pointers handles as may be required.

In the event that the target direction changes, or a new target is designated, the appropriate angular rate control mechanism may be instantly brought to zero by operation of either of the rate reset handles 246 or 246' and reset by operation of the trainers or pointers handles.

The embodiment described above is presented merely as being illustrative of the invention, and the latter is not intended to be in any way limited thereby except as defined in the appended claims.

We claim:

1. In gun fire control apparatus mounted on an unstable platform, the combination of a movable sight thereon, means responsive to the deviation of the platform from a horizontal plane for moving said sight to compensate for said deviation, means for measuring the rate of movement in bearing of a moving target, means for integrating the measured rate over elapsed time, means for modifying the integrated rate in accordance with a function of the angle of elevation to the target, and means responsive to the modified integrated rate for moving the sight in train independently of said stabilizing movement thereof, whereby the sight will follow the moving target as if mounted on a stable platform.

2. In gun fire control apparatus mounted on an unstable platform, the combination of a movable sight thereon, means responsive to the deviation of said platform from a horizontal plane for moving said sight to compensate for said deviation, means for measuring in a slant plane to the target the rate of movement in bearing of the target, means for integrating the measured rate over elapsed time, means for dividing the integrated rate by the cosine of angle of elevation of the target, and means actuated in accordance with the divided integrated rate for moving the sight in train independently of said stabilizing movement thereof, whereb the sight will follow the moving target as if mounted on a stable platform.

3. In gun fire control apparatus mounted on an unstable platform, the combination of a movable sight thereon, means responsive to the deviation of said platform from a horizontal plane for moving said sight to compensate for said deviation, means for measuring the rate of movement in elevation of a moving target, means for integrating the measured rate over elapsed time, means responsive to the integrated rate for moving the sight in elevation independently of said stabilizing movement thereof, means for measuring in a slant plane to the target the rate of movement in bearing of the target, means for integrating the measured rate over elapsed time, means for dividing the integrated rate by the cosine of the angle of elevation of the target, and means actuated by the divided integrated rate for moving the sight in train independently of said stabilizing movement thereof, whereby the sight is moved in train and elevation to follow the target as if mounted on a stable platform.

4. In gun fire control apparatus mounted on an unstable platform, the combination of a movable sight thereon, means responsive to the deviation of the unstable platform from a horizontal plane for moving the sight to compensate for said deviation, means for measuring the rate of movement in elevation of a moving target, means for integrating the measured rate over elapsed time, and means responsive to the integrated rate for moving the sight in elevation independently of said stabilizing rnovement thereof, whereby th'esrgfit'wilrfnow the targt"as"if mounted on a stable platform.

5. In gun fire control apparatus mounted on an unstable platform, the combination of a movable sight thereon, means responsive to the deviation of the unstable platform from a horizontal plane for moving the sight to compensate for said deviation, means for measuring the rate of movement in elevation of a moving target, means for integrating the measured rate over elapsed time, means responsive to the integrated rate for moving the sight in elevation, means for measuring in a slant plane to the target the rate of movement in bearing of the target, means for integrating the measured rate over elapsed time, means for dividing the integrated rate by the cosine of the angle of elevation of the target, and means actuated by the divided integrated rate for moving the sight in train, whereby the optical sight may be moved in train and in elevation independently of said stabilizing movement thereof to follow the target as if mounted on a stable horizontal platform.

6. In gun fire control apparatus for use on an unstable platform, the combination of a movable sight therefor, a gXrSq2PE X s t m gx mamcalmreference,,plane.relativelxlt 12 first gyroscopic system and said sight for stabilizing the latter in a vertical plane.

'7. In gun fire control apparatus, the combination of a sight, means for moving the sight manually in accordance with the movements of a target, independent driving means, connections between said driving means and said sight, a variable speed means in said connections having an adjustable part, operative connections between said manual means and said part whereby the movements of said manual means adjust the speed at which the sight is driven by said driving means, a normally disengaged electrically actuated clutch in the connections between said driving means and said sight, a normally disengaged switch at the said manual means for engaging said clutch during operation of said manual means to transfer the drive of said sight to said driving means, and calculating mechanism actuated by said driving means in accordance with the movements of said sight for continuously providing target rate for use in determining data for laying the gun.

8'. In gun fire control apparatus, the combination of sighting means, driving means, connections between said driving means and sighting means for driving the latter in elevation, variable speed mechanism in said connections, single manually operable means for adjusting said mechanism to vary the speed of movement of said sighting means in elevation, a second driving means, second connections between said driving means and sighting means for driving the latter in train, second variable speed mechanism in said second connections, second single manually operable means for adjusting said second mechanism to vary the speed of movement of said sighting means in train, means interposed between said second variable speed mechanism and said sighting means for modifying the movement of the sighting means in train, and operative connections between said first connections and said last-named means for operating the latter in accordance with the movements of the sighting means in elevation.

9. In gun fire control apparatus mounted on an unstable platform, the combination of sighting means, a variable speed driving means having an adjustable part, connections between said driving means and sighting means for driving the latter in elevation, manually operable means for adjusting the said adjustable part of said mechanism to vary the speed of movement of said sighting means in elevation, a second variable speed driving means having an adjustable part. second connections between said driving means and sighting means for driving the latter in train, second manually operable means for adjusting the said adjustable part of said second mechanism to vary the speed of movement of said sighting means in train, a stable element, operative connections between said element and said first connections for stabilizing said sighting means against movements of said platform in a vertical plane normal to the line of sight and the target, and operative connections between said element and said second connections for stabilizing said sighting means against movement of said platform in a vertical plane in the line sight to the target.

10. In gun fire control apparatus, the combination of a rotatable support about a vertical axis, a sight thereon movable in elevation, driving means for rotating said support, whereby said sight is driven in train, a normally disengaged clutch interposed between said driving means and said support, manually operable means for driving said support in train independently of said driving means, a variable speed means interposed between said support and said driving means and having an adjustable part, operative connections between said manually operable means and said part for adjusting said variable speed means in accordance with the movements of the target in train, means for engaging said clutch and operable at will for transferring the drive of said support in train to said driving means, second driving means for actuating said sight in elevation, a second normally disengaged clutch interposed between said second driving means and said sight, second manually operable means for actuating said sight in elevation independently of said second driving means, second variable speed means interposed between said sight and said second driving means and having an adjustable part, operative connections between said second manually operable means and ARTHUR P. DAVIS. JAMES K. MACOMBER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,464,208 Makarofi Aug. 7, 1923 1,468,712 Ford Sept. 25, 1923 1,831,595 Gray Nov. 10, 1931 1,849,611 Bussei Mar. 15, 1932 2,071,424 Papello Feb. 23, 1937 2,105,985 Papello Jan. 18, 193 

